Catheters may be located in various venous locations and cavities throughout the body. Central venous catheters, for example, are placed in four common locations within the chest and/or in the femoral vessels. They may be placed in either the right or left subclavian vein or in the right or left internal jugular vein.
In order to place a catheter in a particular location, a physician uses various techniques. To determine the location of some vessels, for example, a physician may predict the location by physical body landmarks present on the body surface for vessels which are not themselves visible on the body surface. Using landmarks, vessels may be cannulated by first identifying the vessels by aspiration with a long hollow needle. When blood enters a syringe attached to the needle, the syringe is disconnected and a guide wire is passed through the needle into the hollow passage, or lumen, of the vessel. The needle is then removed leaving the guide wire within the vessel. The guide wire projects beyond the surface of the skin.
Several options are then available to a physician for venous catheter placement. The simplest is to pass a catheter into the vessel directly over the guide wire. The guide wire is then removed leaving the catheter in position within the vessel. This technique is typically used when the catheter is of a relatively small diameter, made of a stiff material and not significantly larger than the guide wire. If the catheter is significantly larger than the guide wire, a dilator device is first passed over the guide wire to enlarge the hole following which the catheter is passed over the guide wire and the guide wire removed.
A further option requires an introducer sheath. This is simply a large, stiff thin-walled catheter which serves as a temporary conduit for the permanent catheter which is being placed. The introducer sheath is positioned by placing a dilator device inside of the introducer and passing both the dilator and the introducer together into the vessel. The guide wire and dilator are then removed leaving the thin-walled introducer sheath in place. A catheter such as a Swan-Ganz catheter into which a guide wire cannot be placed or a large silicone catheter such as a Tesio catheter can then be placed through this dilator sheath.
In the case of the Swan-Ganz catheter, the introducer sheath has a hemostasis valve at its proximal end and is simply left in place to function as part of the intravenous system.
In the case of a Tesio catheter, a physician would not leave the stiff, thin-walled catheter in place. Therefore, a straight catheter without a hub or an anchoring device is passed through the sheath and into the vessel. The sheath is removed over the catheter. However, if a hub or any type of anchoring device such as a cuff is permanently attached to the catheter, the sheath must be very large or comprise a tear-away portion which splits into two parts as the sheath is retracted.
Although the larger or the tear-away sheaths work, they are associated with unwanted bleeding and the tear-away sheath tends to pull the catheter out of the vein as the sheath is removed. As a result, there is a need in the art for an anchoring device which can be utilized after the sheath has been removed which enables a physician to use a preferred small diameter, non-tear-away sheath for insertion of certain venous catheters which eliminates the disadvantages associated with large diameter or tear-away sheaths.
A typical anchoring device for these catheters and other venous and body cavity catheters and shunts involves use of a tissue ingrowth cuff fitted on the catheter for stabilization of a catheter in a single position if the catheter is to be left in that position for a significant length of time. Surrounding tissue cells grow into the fabric stabilizing the catheter in a particular location. In using catheters having fabric cuff fittings, it is common to create a subcutaneous tunnel or similar opening several centimeters caudal to the insertion site of the catheter for stabilization of the catheter using the cuff. Subcutaneous tunnels are typically used with insertion of Tesio catheters, for example.
Once the catheter is inserted in a blood vessel or other location, the skin is anaesthetized in a linear fashion for a distance of about 6-8 centimeters caudal to the insertion site. If tunneling is used for venous insertion, a second incision is made and a tunneling device is passed into the incision and out through the skin at the point of catheter insertion creating a subcutaneous tunnel. The catheter is attached to the tunneling device and pulled back through the skin tunnel. A cuff is typically designed to lie in the medial portion of the subcutaneous tunnel. Similarly, when inserting catheters in body cavities and other locations, some catheters are designed such that the cuff is affixed to the catheter in an area which corresponds to a typical area chosen by a physician for subcutaneous securement.
While providing satisfactory anchoring in some situations, catheters manufactured with fabric cuffs already affixed are only available in several set lengths having the cuffs located in areas designed to correspond to average patient sizes. The cuffs are not adjustable to all body sizes and types for optimal positioning. The cuffs are not locatable or movable along the catheter to adjust for placement discrepancies. As most patients vary in size, internal distances involved in subcutaneous placement vary accordingly, deviating from the standard catheter cuff locations commercially available and making stable securement difficult in many cases.
In addition, as the cuff cannot be moved, the physician may have to adjust the catheter itself within the vein to align the cuff within a stable area for securement. Positioning of the catheter is particularly important to proper catheter functioning. For example, if the tip of a central venous catheter is not properly located within a vessel, the catheter may cause the condition of cardiac arrhythmia or otherwise inhibit blood flow. If the catheter tip is not properly located within a body cavity there may not be sufficient access to the tip to allow bodily fluid to properly flow through the catheter.
A need is therefore present for an anchoring device which is locatable within a subcutaneous tunnel or other subcutaneous location for securing a catheter such that the device can be placed by the physician in the most stable position for subcutaneous securement of the catheter without the need to move the catheter itself or to depend upon available commercial sizes of catheters having cuffs already affixed in positions for only average patient sizes. It is also preferable to have an anchoring device which is attachable after insertion of a catheter to obviate the need for large diameter or tear-away sheaths used with certain catheters.